PCR data. Quantitative PCR data correlate closely with microarray expression profiles emphasizing large scale changes in expression prior to the peak proliferative response at 96 hours after stimulation, whereas unstimulated controls do not show this pattern. F5 Rag^−/− splenocytes were transferred by intravenous injection into C57BL/6 mice that were infected 24 hours later with recombinant vaccinia virus expressing NP366-374. Spleens were collected from these mice at time points up to 192 hours after infection and epitope-specific cells sorted by flow cytometry. Quantitative PCR of 14 selected genes was performed using the Roche Lightcycler system. Gene expression ratios were calculated using G6PDX as an housekeeping gene. Dotted lines represent quantitative PCR of the same genes in unstimulated controls. In the cases of CDK4, cyclin A2, cyclin G2, IL-1β IL-1R2, CXCR3, and CXCR6, gene expression ratios were very low at time point 0 and were not detectable in unstimulated control mice at any further time points. Graphs represent data from 3 mice per time point, with error bars showing the standard error.